NULL在oracle中有不同的地方

Question

我有一種情況，我想從客戶表中返回空值，並且實質上是從賬單表中選擇不同的賬單代碼。

我該怎麼做？

表客戶

 
ID 
Name 
CustNumber 
BILLCODE 

表比爾

 
ID 
BILLCODE 

我試圖做類似

Select Null ID, Null NAME, Null CUSTNUMBER 
from CUSTOMER 
RIGHT JOIN ID, BILLCODE 
on customer.billcode = bill.billcode 

我只希望在表中的每個billcode 1分的紀錄。

Answer 1

with billcodes as (select distinct billcode from bill) 
select b.billcode, c.id, c.name, c.custnumber 
from billcodes b 
left outer join customer c on c.billcode=b.billcode 

或者：

select b.billcode, c.id, c.name, c.custnumber 
from (select distinct billcode from bill) b 
left outer join customer c on c.billcode=b.billcode 

Answer 2

我猜測的問題是：我怎麼才能回報所有客戶從客戶表與他們有各自的法案代碼列表？

如果是的話，你想用group by和left outer join：

select b.billcode, c.id, c.name, c.custnumber 
from customer c left outer join 
    bill b 
    on c.billcode = b.billcode 
group by b.billcode, c.id, c.name, c.custnumber